1. Field of the Invention
The present invention relates to ink jet recording ink and an ink jet recording method, and more particularly to ink jet recording ink and an ink jet recording method which can provide an image having a high optical density without unevenness, feathering and bleeding, clogging of the nozzles and disorder in discharging ink.
2. Description of the Related Art
A so-called ink jet recording apparatus capable of recording an image on paper, cloth or a film by discharging liquid or molten solid ink through nozzles, slits, a porous film or the like has been energetically investigated because of advantages of small size, low cost and low noise. Recently, a multiplicity of ink jet recording apparatuses capable of performing a full color recording operation have been put on the market and widely used in the field of the recording apparatus, as well as black monochrome printer capable of realizing excellent print quality on so-called plain paper, such as a report sheet and a copy sheet.
Ink for use in the ink jet recording apparatus is mainly composed of solvent, a coloring material and additives. The ink for use in the ink jet recording operation is required to satisfy:
(1) An image having a high optical density and a high resolution without unevenness and free from feathering and bleeding and fogging can be obtained on a paper sheet. PA0 (2) The leading end of a nozzle must not be clogged with dried ink to provide good discharge responsiveness and ink discharging stability. PA0 (3) The ink must quickly be dried on the paper sheet. PA0 (4) The formed image must have excellent fastness. PA0 (5) Excellent storage stability can be obtained for a long time.
As for the requirement (1), a variety of means have been developed. For example, a method has been disclosed in, for example, Japanese Patent Application Laid-Open (JP-A) No. 63-132083 in which a solid material, composed of polyethylene glycol, fatty acid and its salt, having a molecular weight of 300 or greater and arranged such that the viscosity ratio of 10% solution to 30% solution is 1:3 or higher, is used to raise the viscosity of ink so as to prevent feathering. In U.S. Pat. No. 5,133,803, a bleed preventing method has been suggested in which a colloid substance, having a high molecular weight of 10,000 or more, composed of alginic acid, carboxymethylcellulose, carrageenan and the like is used. In Japanese Patent Application Laid-Open (JP-A) No. 6-136306, a method has been suggested in which a polymeric substance having a molecular weight of 3000 to 50000 is used to make the surface tension and the viscosity of ink to be specific values so as to obtain satisfactory fixation characteristic and prevent feathering and bleeding.
Although a variety of contrivances have been suggested to prevent image feathering and bleeding, a method capable of satisfying requirements when used to record an image on a recording medium, which easily causes feathering and bleeding, has not been obtained. Moreover, a method capable of satisfying all of the other requirements which ink for ink jet recording must satisfy has not been obtained.